US20110095001A1 - Thermal Material-Processing Method - Google Patents
Thermal Material-Processing Method Download PDFInfo
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- US20110095001A1 US20110095001A1 US12/910,226 US91022610A US2011095001A1 US 20110095001 A1 US20110095001 A1 US 20110095001A1 US 91022610 A US91022610 A US 91022610A US 2011095001 A1 US2011095001 A1 US 2011095001A1
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- 238000003672 processing method Methods 0.000 title abstract description 7
- 238000010894 electron beam technology Methods 0.000 claims abstract description 74
- 230000033001 locomotion Effects 0.000 claims abstract description 61
- 238000007669 thermal treatment Methods 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 31
- 238000003466 welding Methods 0.000 claims description 15
- 238000003384 imaging method Methods 0.000 claims description 5
- 230000001143 conditioned effect Effects 0.000 abstract description 3
- 238000012937 correction Methods 0.000 description 13
- 230000008901 benefit Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K15/00—Electron-beam welding or cutting
- B23K15/0046—Welding
- B23K15/0053—Seam welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K15/00—Electron-beam welding or cutting
- B23K15/0013—Positioning or observing workpieces, e.g. with respect to the impact; Aligning, aiming or focusing electronbeams
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K15/00—Electron-beam welding or cutting
- B23K15/02—Control circuits therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
- H01J37/3002—Details
- H01J37/3005—Observing the objects or the point of impact on the object
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
- H01J37/304—Controlling tubes by information coming from the objects or from the beam, e.g. correction signals
- H01J37/3045—Object or beam position registration
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/30—Electron or ion beam tubes for processing objects
- H01J2237/31—Processing objects on a macro-scale
- H01J2237/3104—Welding
Definitions
- the invention relates to a material-processing method wherein
- the geometrical deviations may be both the cause of an inaccurate clamping of the workpiece and also the consequence of tolerance deviations to which the workpiece is subject in the course of manufacture.
- the consequence of these geometrical deviations is that although the working spot of the electron beam follows the ideal processing contour correctly, it does not strike the real processing contour or does not strike it everywhere.
- a second cause of deviations between the working spot of the electron beam and the actual processing contour may consist in the fact that a residual magnetisation is present in the workpiece, under the influence of which the electron beam is deflected. This has the consequence that the working spot of the electron beam does not strike the actual processing contour, even when the latter follows the stored ideal processing contour.
- said working spot would have to be controlled in accordance with control variables that corresponds to a processing contour possibly deviating both from the ideal processing contour and from the actual processing contour, which here is called the ‘effective’ processing contour. If a magnetic deflection of the electron beam is eliminated, the effective processing contour corresponds to the actual processing contour.
- the present invention is directed to resolving these and other matters.
- An object of the present invention is to configure an electron-beam material-processing method of the type stated in the introduction in such a way that the deviation of the effective processing contour from the ideal processing contour is presented in readily comprehensible manner and in this way there is also the possibility of simple correction of this deviation.
- this object may be achieved in that
- control variables in the sense of feature c) stated in the introduction is understood to mean all parameters that the control device generates for the purpose of inducing a certain relative motion between the focus of the electron beam and the workpiece. In this connection it is a question, in particular, of the magnitude and the temporal progression of control currents and/or control voltages that are used for deflecting the electron beam and/or for the mechanical motion of electron beam and/or workpiece.
- a kind of ‘unwinding’ of the processing contour is generated in such a manner that irrespective of the actual, generally curved, path of the processing contour the ideal processing contour is always represented as a straight line, and the deviation of the effective processing contour from the ideal processing contour is always represented as a deviation from the straight-line shape.
- This is readily comprehensible, in particular also for unskilled or only semi-skilled operators, and, in addition, represents a shape that is particularly well-suited for a subsequent correction of the deviations.
- the effective processing contour which takes account of both geometrically and magnetically conditioned deviations of the ‘incidence track’ of the electron beam from the ideal processing contour on the workpiece, is ascertained in the same device that also implements the actual material-processing method. This signifies multiple advantages in comparison with a photo-optical method for determining the actual processing contour. On the one hand, the expenditure on equipment is very much lower, since in general all the requisite components are present anyway in the electron-beam equipment.
- the method according to the invention is also superior to a photo-optical method for the reason that the electron beam employed for determining the effective processing contour ‘sees’ the processing contour just as the electron beam also does in the course of the subsequent actual processing of material, so that, in particular, magnetic deflections that cannot be detected by photo-optical means are also given consideration.
- the method according to the invention is particularly well-suited for the welding of two structural components, wherein the processing contour is accordingly a groove between two structural components to be joined to one another so as to form a workpiece.
- the setting of the control variables in accordance with step e) can in many cases be undertaken empirically, since after brief experience with the system the type of the requisite correction of the control variables can be inferred from the shape of the ascertained effective processing contour. In each case, after each correction of the control variables it is readily possible to recognise whether or not the (new) effective processing contour has approximated to the desired shape of a straight line. In the case of certain characteristic deviations, algorithms can also be developed with which the deviations can be reduced to a tolerable extent.
- the relative motion between the working spot of the electron beam and the workpiece may be effected mechanically by motion of the workpiece and/or of the electron-beam source together with imaging elements. A not inconsiderable expenditure on equipment is required for this; the motion is comparatively sluggish.
- the relative motion between the working spot of the electron beam and the workpiece may be effected electrically by deflecting the electron beam. This is possible with comparatively little expenditure on equipment and without inertia, but is understandably subject to geometrical limits. In each case it is expedient to implement at least the scan motion electrically by appropriate deflection of the electron beam.
- FIG. 1 is a schematic drawing for a unit for electron-beam welding.
- FIG. 2 is a top view of a workpiece which comprises two structural components to be welded together.
- FIG. 3 is a schematic drawing of the scan operation that precedes the actual electron-beam welding.
- FIG. 4 is a graphical representation of a signal obtained in the course of the scan operation at a point at which the gauged, effective groove coincides with the programmed, ideal groove path.
- FIG. 5 is a graphical representation of a signal obtained in the course of the scan operation at a point at which the gauged, effective groove deviates from the programmed, ideal groove path.
- FIG. 6 is a schematic drawing of the ‘unwound’ effective groove path prior to a correction of the deviations from the ideal groove path.
- FIG. 7 is a schematic drawing of the ‘unwound’ effective groove path after the correction.
- FIG. 1 This shows a unit for electron-beam welding, labelled overall by reference symbol 1 , as is known as such. It will therefore be sufficient to describe it briefly.
- the unit 1 comprises, in a vacuum-tight housing which is not represented, from top to bottom an electron-beam source 2 , a centering and stigmator unit 3 including various deflecting electrodes, a focusing lens 4 comprising suitable coils, and also x-y deflection coils 5 .
- the workpiece 6 stands on a manipulator 7 with which it can be moved in the x-y plane by means of a motor and with high precision.
- output signals for various amplifiers 10 are generated in addition which, in turn, again apply suitable currents and voltages to the centering and stigmator unit 3 , to the focusing lens 4 , to the deflection coils 5 and also to the manipulator 7 .
- the electron beam 11 can be focused onto the workpiece 6 , and its working spot which has arisen in this way can be moved on the workpiece 6 .
- sensor plates 12 which are capable of detecting the electrons back-scattered from the workpiece 6 .
- an image of the workpiece 6 can, for example, be generated that is quite similar to an optical image, as is known in the state of the art.
- the welding method according to the invention can now be implemented as described in the following.
- the description is given on the basis of an exemplary workpiece 6 which is represented in FIG. 2 and which comprises two structural components 6 a and 6 b to be welded together.
- the ideal welding groove 13 which, in the case of welding, constitutes the processing contour and which is saved in the control device 9 of the unit 1 .
- the working spot of the electron beam 11 does not follow the ideal groove path 13 but rather follows an effective groove path 14 which deviates from the ideal groove path 13 in the regions represented in dotted manner.
- an image or partial image of the workpiece 6 is generated which enables a determination of the coarse position of the workpiece 6 in the system-specific coordinate system of the unit 1 . If this position differs considerably from a stored specified position, the workpiece 6 is pushed closer to the specified position with the aid of the manipulator 7 .
- FIG. 3 a section of the ideal groove path between the two structural components 6 a , 6 b to be welded together is represented by the relatively thin line 13 , which, as already mentioned above, is programmed within the control device 9 in suitable manner.
- the somewhat thicker line 14 the corresponding section of the ‘effective’ groove path is represented which by reason of various influences deviates from the ideal groove path 13 .
- deviations of such a type are based on genuine geometrical deviations of the real groove path, which, in turn, may lie their cause in a faulty clamping of the workpiece 6 on the manipulator 7 , or in manufacturing tolerances of the structural components 6 a , 6 b to be welded together.
- the deviation of the effective groove path 14 from the ideal groove path 13 may, however, also have non-geometrical reasons, namely when in the case of magnetic structural components 6 a , 6 b the electron beam 11 is deflected by an existing residual magnetism in such a way that the ideal groove 13 is not correctly struck by the electron beam 11 .
- the working spot of the electron beam 11 is moved, with diminished energy density and/or at higher speed, which does not suffice for welding, along the ideal groove path 13 , whereby on this feed motion there is superimposed a scan motion 15 and 16 , respectively, running perpendicular to the respective tangential direction of the ideal groove path 13 .
- This scan motion 15 and 16 respectively, extends on both sides beyond the ‘ideal’ groove path 13 by an amplitude a (cf. FIGS. 3 and 4 ).
- an intensity signal is recorded with the aid of the sensor plates 12 of the unit 1 .
- certain intensity fluctuations arise as a function of the deflection of the working spot from the ideal groove path 13 .
- FIG. 3 let point A of the ideal groove path 13 be considered, at which the ideal groove path 13 coincides with the effective groove path 14 .
- the progression of the intensity of the back-scattered electron beam 11 ascertained with the aid of the sensor plates 12 , looks as represented in FIG. 4 .
- a pronounced minimum is situated at the ‘zero’ point—that is to say, at the point at which the scan motion 15 of the electron beam 11 just crosses the ‘ideal’ groove path 13 .
- the intensity curves as shown in FIGS. 4 and 5 For the purpose of readily comprehensible representation of the effective groove path 14 , use is not made of the intensity curves as shown in FIGS. 4 and 5 . Rather, a representation is chosen that corresponds to an image of the workpiece 6 in the neighborhood of the ideal groove path 13 .
- the intensity progressions according to FIGS. 4 and 5 are converted into tonal values.
- the tonal values obtained in the course of the various scan motions are put together in a manner as represented in FIG. 6 .
- This Figure shows, in particular, the tonal-value distributions at the 46 reference points of FIG. 2 .
- the location of the effective groove path 14 is recognisable by means of a wide dark line.
- This ‘standardisation’ of the graphical representation of the ‘unwound’ effective groove path 14 also facilitates the correction of the control variables of the control device 9 in such a manner that the deviations of the effective groove path 14 from the ideal groove path 13 are reduced.
- empirical findings frequently suffice in order to be able to implement successful amendments of the control variables.
- a further scan operation implemented after such an amendment makes it immediately clear whether the corrections of the control variables that were undertaken went in the right direction or not—that is to say, whether or not the graphical representation of the effective groove path 14 has approximated better to the straight-line shape.
- the electron beam 11 can now be guided without difficulty along the effective groove path 14 with sufficient energy density in the working spot and/or at correspondingly lower speed for the actual welding operation, so that the structural components 6 a , 6 b situated on both sides of the effective groove path 14 can be joined together in highly precise manner.
- the relative motion between working spot of the electron beam 11 and the workpiece 6 may be effected by deflection of the electron beam also by mechanical motion of the workpiece 6 on the manipulator 7 or also by mechanical motion of the electron-beam source 2 with the associated imaging elements 3 , 4 , 5 , 12 .
Abstract
Description
- This application claims the filing benefit of German Patent Application No. 10 2009 050 521.0 filed Oct. 23, 2009 the contents of which are incorporated herein by reference.
- The invention relates to a material-processing method wherein
-
- a) an electron beam is focused onto the surface of a workpiece:
- b) between the working spot of the electron beam and the workpiece a relative motion is brought about, in the course of which the working spot follows a processing contour;
- c) the relative motion between working spot and workpiece is controlled in accordance with control variables that a control device derives from a stored ideal processing contour.
- The quality of a thermal processing brought about with the aid of an electron beam—for example, a weld—depends to a great extent on how accurately the working spot of the electron beam strikes the desired processing contour—in the case of the welding of two structural components, the groove path between the structural components to be welded—in the course of its relative motion in relation to the workpiece. In known material-processing methods of the type specified in the introduction, inaccuracies in this respect occur for differing reasons. A first reason consists in geometrical deviations between the actual processing contour and the expected processing contour stored in the control device, which in the following is also called the ‘ideal’ processing contour.
- The geometrical deviations, in turn, may be both the cause of an inaccurate clamping of the workpiece and also the consequence of tolerance deviations to which the workpiece is subject in the course of manufacture. The consequence of these geometrical deviations is that although the working spot of the electron beam follows the ideal processing contour correctly, it does not strike the real processing contour or does not strike it everywhere. A second cause of deviations between the working spot of the electron beam and the actual processing contour may consist in the fact that a residual magnetisation is present in the workpiece, under the influence of which the electron beam is deflected. This has the consequence that the working spot of the electron beam does not strike the actual processing contour, even when the latter follows the stored ideal processing contour. These magnetically conditioned deviations therefore result in a behaviour that—judging from the outcome at any rate—is tantamount to a geometrical deviation of the actual processing contour from the ideal processing contour. A further cause of the working spot not striking the actual processing contour, or not striking it everywhere, may consist in errors in the programming of the motion.
- In order to ensure that the working spot of the electron beam impinges everywhere on the actual processing contour, said working spot would have to be controlled in accordance with control variables that corresponds to a processing contour possibly deviating both from the ideal processing contour and from the actual processing contour, which here is called the ‘effective’ processing contour. If a magnetic deflection of the electron beam is eliminated, the effective processing contour corresponds to the actual processing contour.
- The present invention is directed to resolving these and other matters.
- An object of the present invention is to configure an electron-beam material-processing method of the type stated in the introduction in such a way that the deviation of the effective processing contour from the ideal processing contour is presented in readily comprehensible manner and in this way there is also the possibility of simple correction of this deviation.
- In accordance with the invention, this object may be achieved in that
-
- d) prior to the actual welding operation a determination of the effective processing contour is undertaken, in that
- da) the working spot of the electron beam executes a relative motion in relation to the workpiece in accordance with the stored data of the ideal processing contour with operating parameters that do not suffice for thermal treatment;
- db) on this relative motion corresponding to the ideal processing contour there is superimposed at a plurality of points a scan motion which is directed transversely to the ideal processing contour and reaches beyond the latter on both sides;
- dc) the intensity of the electron beam back-scattered from the workpiece is measured as a function of the deflection of the scan motion;
- dd) the intensity dependences ascertained in step dc, which were measured in the course of the various scan motions, are placed side by side in such a way that a graphical representation of the workpiece arises in which the progress of the relative motion in the direction of the processing contour is plotted on one axis and the deviation of the effective processing contour from the ideal processing contour is plotted in a second axis.
- d) prior to the actual welding operation a determination of the effective processing contour is undertaken, in that
- When ‘operating parameters’ are mentioned above under da), in particular the energy density in the working spot of the electron beam and/or the velocity of the relative motion between the working spot and the workpiece are/is meant thereby.
- The term ‘control variables’ in the sense of feature c) stated in the introduction is understood to mean all parameters that the control device generates for the purpose of inducing a certain relative motion between the focus of the electron beam and the workpiece. In this connection it is a question, in particular, of the magnitude and the temporal progression of control currents and/or control voltages that are used for deflecting the electron beam and/or for the mechanical motion of electron beam and/or workpiece.
- With the method according to the invention a kind of ‘unwinding’ of the processing contour is generated in such a manner that irrespective of the actual, generally curved, path of the processing contour the ideal processing contour is always represented as a straight line, and the deviation of the effective processing contour from the ideal processing contour is always represented as a deviation from the straight-line shape. This is readily comprehensible, in particular also for unskilled or only semi-skilled operators, and, in addition, represents a shape that is particularly well-suited for a subsequent correction of the deviations.
- In accordance with the invention the effective processing contour, which takes account of both geometrically and magnetically conditioned deviations of the ‘incidence track’ of the electron beam from the ideal processing contour on the workpiece, is ascertained in the same device that also implements the actual material-processing method. This signifies multiple advantages in comparison with a photo-optical method for determining the actual processing contour. On the one hand, the expenditure on equipment is very much lower, since in general all the requisite components are present anyway in the electron-beam equipment. But, furthermore, the method according to the invention is also superior to a photo-optical method for the reason that the electron beam employed for determining the effective processing contour ‘sees’ the processing contour just as the electron beam also does in the course of the subsequent actual processing of material, so that, in particular, magnetic deflections that cannot be detected by photo-optical means are also given consideration.
- The method according to the invention is particularly well-suited for the welding of two structural components, wherein the processing contour is accordingly a groove between two structural components to be joined to one another so as to form a workpiece.
- It is particularly easy to add to the detection of the deviations of the effective processing contour from the ideal processing contour a correction step with which the deviations for the thermal treatment are corrected. Said correction step is distinguished in that, after step d),
-
- e) the control variables corresponding to the ascertained effective processing contour are set in such a way that in the course of the progress of the relative motion in the direction of the effective processing contour the working spot of the electron beam lies everywhere on said contour;
- f) the relative motion between the working spot of the electron beam and the workpiece is then implemented again with operating parameters that are suitable for thermal treatment.
- The setting of the control variables in accordance with step e) can in many cases be undertaken empirically, since after brief experience with the system the type of the requisite correction of the control variables can be inferred from the shape of the ascertained effective processing contour. In each case, after each correction of the control variables it is readily possible to recognise whether or not the (new) effective processing contour has approximated to the desired shape of a straight line. In the case of certain characteristic deviations, algorithms can also be developed with which the deviations can be reduced to a tolerable extent.
- The relative motion between the working spot of the electron beam and the workpiece may be effected mechanically by motion of the workpiece and/or of the electron-beam source together with imaging elements. A not inconsiderable expenditure on equipment is required for this; the motion is comparatively sluggish.
- Alternatively or additionally, the relative motion between the working spot of the electron beam and the workpiece may be effected electrically by deflecting the electron beam. This is possible with comparatively little expenditure on equipment and without inertia, but is understandably subject to geometrical limits. In each case it is expedient to implement at least the scan motion electrically by appropriate deflection of the electron beam.
- When it was stated above that the direction of the scan motion is to be transverse to the direction of the ideal processing contour, this does not inevitably mean a right angle. In many cases, although for reasons of evaluation it will be expedient if the direction of the scan motion is perpendicular to the tangent to the corresponding point of the ideal processing contour, in principle arbitrary other angles also enter into consideration.
- It may happen that in the course of the clamping of the workpiece a relatively coarse incorrect positioning is effected. In this case a procedure may prove useful in which prior to the determination of the effective processing contour with the aid of the back-scattered electron beam an image of the workpiece is generated and thereby information is obtained about the position thereof in a system-specific coordinate system, and in which deviations of this position from a specified position are then compensated mechanically or electronically. In principle it would in fact be possible to manage without this ‘pre-positioning’ if only the amplitude of the scan motion were sufficiently large. But in general this amplitude is limited, for constructional reasons, so that prior to the ascertainment of the effective processing contour the ‘coarse position’ of the workpiece has to be ‘straightened out’.
- It is to be understood that the aspects and objects of the present invention described above may be combinable and that other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and detailed description of the invention.
-
FIG. 1 is a schematic drawing for a unit for electron-beam welding. -
FIG. 2 is a top view of a workpiece which comprises two structural components to be welded together. -
FIG. 3 is a schematic drawing of the scan operation that precedes the actual electron-beam welding. -
FIG. 4 is a graphical representation of a signal obtained in the course of the scan operation at a point at which the gauged, effective groove coincides with the programmed, ideal groove path. -
FIG. 5 is a graphical representation of a signal obtained in the course of the scan operation at a point at which the gauged, effective groove deviates from the programmed, ideal groove path. -
FIG. 6 is a schematic drawing of the ‘unwound’ effective groove path prior to a correction of the deviations from the ideal groove path. -
FIG. 7 is a schematic drawing of the ‘unwound’ effective groove path after the correction. - While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more embodiments with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated.
- Reference will firstly be made to
FIG. 1 . This shows a unit for electron-beam welding, labelled overall byreference symbol 1, as is known as such. It will therefore be sufficient to describe it briefly. - The
unit 1 comprises, in a vacuum-tight housing which is not represented, from top to bottom an electron-beam source 2, a centering andstigmator unit 3 including various deflecting electrodes, a focusinglens 4 comprising suitable coils, and also x-y deflection coils 5. Theworkpiece 6 stands on amanipulator 7 with which it can be moved in the x-y plane by means of a motor and with high precision. - In a
control device 9, output signals forvarious amplifiers 10 are generated in addition which, in turn, again apply suitable currents and voltages to the centering andstigmator unit 3, to the focusinglens 4, to the deflection coils 5 and also to themanipulator 7. - With the various aforementioned currents or voltages the
electron beam 11 can be focused onto theworkpiece 6, and its working spot which has arisen in this way can be moved on theworkpiece 6. - Below the deflecting
electrodes 5 there are arrangedsensor plates 12 which are capable of detecting the electrons back-scattered from theworkpiece 6. With the aid of thesensor plates 12 an image of theworkpiece 6 can, for example, be generated that is quite similar to an optical image, as is known in the state of the art. - By using the
unit 1 elucidated above with reference toFIG. 1 , the welding method according to the invention can now be implemented as described in the following. The description is given on the basis of anexemplary workpiece 6 which is represented inFIG. 2 and which comprises twostructural components 6 a and 6 b to be welded together. Situated between the twostructural components 6 a, 6 b is theideal welding groove 13 which, in the case of welding, constitutes the processing contour and which is saved in thecontrol device 9 of theunit 1. However, by reason of errors such as were outlined above and such as will be elucidated once again more precisely further below, the working spot of theelectron beam 11 does not follow theideal groove path 13 but rather follows aneffective groove path 14 which deviates from theideal groove path 13 in the regions represented in dotted manner. - Along the
ideal groove path 13various reference points 1 to 46 are indicated which serve for description purposes. - First of all, from the
electron beam 11 back-scattered on theworkpiece 6 an image or partial image of theworkpiece 6 is generated which enables a determination of the coarse position of theworkpiece 6 in the system-specific coordinate system of theunit 1. If this position differs considerably from a stored specified position, theworkpiece 6 is pushed closer to the specified position with the aid of themanipulator 7. - Now the actual welding is prepared in the following manner:
- In
FIG. 3 a section of the ideal groove path between the twostructural components 6 a, 6 b to be welded together is represented by the relativelythin line 13, which, as already mentioned above, is programmed within thecontrol device 9 in suitable manner. By the somewhatthicker line 14 the corresponding section of the ‘effective’ groove path is represented which by reason of various influences deviates from theideal groove path 13. Very frequently, deviations of such a type are based on genuine geometrical deviations of the real groove path, which, in turn, may lie their cause in a faulty clamping of theworkpiece 6 on themanipulator 7, or in manufacturing tolerances of thestructural components 6 a, 6 b to be welded together. The deviation of theeffective groove path 14 from theideal groove path 13 may, however, also have non-geometrical reasons, namely when in the case of magneticstructural components 6 a, 6 b theelectron beam 11 is deflected by an existing residual magnetism in such a way that theideal groove 13 is not correctly struck by theelectron beam 11. - For the purpose of ascertaining the
effective groove path 14, in a scan operation placed ahead of the actual welding operation the procedure is as follows: - The working spot of the
electron beam 11 is moved, with diminished energy density and/or at higher speed, which does not suffice for welding, along theideal groove path 13, whereby on this feed motion there is superimposed ascan motion ideal groove path 13. Thisscan motion groove path 13 by an amplitude a (cf.FIGS. 3 and 4 ). During the feed motion and thescan motion electron beam 11 an intensity signal is recorded with the aid of thesensor plates 12 of theunit 1. In the process, certain intensity fluctuations, such as are represented inFIGS. 4 and 5 , arise as a function of the deflection of the working spot from theideal groove path 13. - First of all, in
FIG. 3 let point A of theideal groove path 13 be considered, at which theideal groove path 13 coincides with theeffective groove path 14. In this case the progression of the intensity of the back-scatteredelectron beam 11, ascertained with the aid of thesensor plates 12, looks as represented inFIG. 4 . A pronounced minimum is situated at the ‘zero’ point—that is to say, at the point at which thescan motion 15 of theelectron beam 11 just crosses the ‘ideal’groove path 13. - On the other hand, the situation is different at point B in
FIG. 3 , at which theideal groove path 13 clearly deviates from theeffective groove path 14. The intensity signal obtained at this point with the aid of thesensor plates 12 is represented inFIG. 5 . Also in this case a clear minimum of the intensity arises, which, however, is located laterally alongside that point at which the working spot of theelectron beam 11 runs over theideal groove path 13. - For the purpose of readily comprehensible representation of the
effective groove path 14, use is not made of the intensity curves as shown inFIGS. 4 and 5 . Rather, a representation is chosen that corresponds to an image of theworkpiece 6 in the neighborhood of theideal groove path 13. For this purpose, for example, the intensity progressions according toFIGS. 4 and 5 are converted into tonal values. The tonal values obtained in the course of the various scan motions are put together in a manner as represented inFIG. 6 . This Figure shows, in particular, the tonal-value distributions at the 46 reference points ofFIG. 2 . The location of theeffective groove path 14 is recognisable by means of a wide dark line. - By reason of the manner of proceeding described above on the basis of
FIG. 3 , in the course of the scan operation a kind of unwinding of theeffective groove path 14 results. If the latter coincides everywhere with theideal groove path 13, a straight line always results—that is to say, irrespective of the geometrical guidance of theideal groove path 13 on theworkpiece 6—by way of image, as shown inFIG. 7 . Deviations of theeffective groove path 14 from theideal groove path 13 are manifested in corresponding deviations of the image from the straight-line shape, as shown inFIG. 6 . - It is obvious that the images obtained as a result of the scan operation permit a very rapid evaluation which is easy to understand, precisely also for the reason that the basic shape of the
ideal groove path 13 in the image—irrespective of the actual geometrical groove path on theworkpiece 6—is always a straight line, and a deviation of theeffective groove path 14 from theideal groove path 13 in the image is always a deviation from the straight-line shape. - This ‘standardisation’ of the graphical representation of the ‘unwound’
effective groove path 14 also facilitates the correction of the control variables of thecontrol device 9 in such a manner that the deviations of theeffective groove path 14 from theideal groove path 13 are reduced. Here, empirical findings frequently suffice in order to be able to implement successful amendments of the control variables. A further scan operation implemented after such an amendment makes it immediately clear whether the corrections of the control variables that were undertaken went in the right direction or not—that is to say, whether or not the graphical representation of theeffective groove path 14 has approximated better to the straight-line shape. - In many cases it is also possible to assign to certain shapes of the deviations of the
effective groove path 14 from theideal groove path 13 an algorithm with which the new control variables can be calculated that are suitable for a correction of the guidance of theelectron beam 11. - Once the scan operation that has been described has been concluded and the new control variables that are suitable for the correction have been set in the
control device 9, theelectron beam 11 can now be guided without difficulty along theeffective groove path 14 with sufficient energy density in the working spot and/or at correspondingly lower speed for the actual welding operation, so that thestructural components 6 a, 6 b situated on both sides of theeffective groove path 14 can be joined together in highly precise manner. - Instead of being effected electronically, the relative motion between working spot of the
electron beam 11 and theworkpiece 6 may be effected by deflection of the electron beam also by mechanical motion of theworkpiece 6 on themanipulator 7 or also by mechanical motion of the electron-beam source 2 with the associatedimaging elements - As already mentioned above, the welding of two structural components is only one example of a thermal material-processing method. The manner of proceeding in other methods is, however, fundamentally the same, in which connection in the above description the more general term ‘processing contour’ then takes the place of the more specific term ‘groove path’.
- The above description of the invention was given on the basis of an example in which deviations of the effective processing contour from the ideal processing contour were present in one direction only. However, the method according to the invention is also suitable for cases in which deviations of the effective processing contour from the ideal processing contour are present also in a further direction. Deviations of such a type are manifested in local blurred regions of the image according to
FIG. 6 or 7. The correction in this direction is effected in such a way that these images become sharp over their entire extent.
Claims (20)
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DE102009050521.0 | 2009-10-23 | ||
DE102009050521.0A DE102009050521B4 (en) | 2009-10-23 | 2009-10-23 | Thermal material processing process |
DE102009050521 | 2009-10-23 |
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US20110095001A1 true US20110095001A1 (en) | 2011-04-28 |
US8314358B2 US8314358B2 (en) | 2012-11-20 |
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US12/910,226 Active 2031-05-24 US8314358B2 (en) | 2009-10-23 | 2010-10-22 | Thermal material-processing method |
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US (1) | US8314358B2 (en) |
EP (1) | EP2314410B1 (en) |
CN (1) | CN102039483B (en) |
DE (1) | DE102009050521B4 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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CN104503380A (en) * | 2014-11-19 | 2015-04-08 | 中国科学院空间科学与应用研究中心 | Container-less material processing system |
CN106918834A (en) * | 2017-03-28 | 2017-07-04 | 核工业理化工程研究院 | The accurate measurement method of sweep trace of electron beam |
US11377706B2 (en) * | 2011-12-27 | 2022-07-05 | Jfe Steel Corporation | Device to improve iron loss properties of grain-oriented electrical steel sheet |
Families Citing this family (4)
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US8502172B1 (en) * | 2012-06-26 | 2013-08-06 | Fei Company | Three dimensional fiducial |
DE102014004035A1 (en) * | 2014-03-21 | 2015-10-08 | Probeam Ag & Co. Kgaa | Method for producing small holes in workpieces |
AU2018273352B2 (en) | 2017-05-22 | 2023-07-27 | Howmedica Osteonics Corp. | Device for in-situ fabrication process monitoring and feedback control of an electron beam additive manufacturing process |
EP3597333A1 (en) | 2018-07-19 | 2020-01-22 | Howmedica Osteonics Corporation | System and process for in-process electron beam profile and location analyses |
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- 2010-10-22 US US12/910,226 patent/US8314358B2/en active Active
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US11377706B2 (en) * | 2011-12-27 | 2022-07-05 | Jfe Steel Corporation | Device to improve iron loss properties of grain-oriented electrical steel sheet |
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CN106918834A (en) * | 2017-03-28 | 2017-07-04 | 核工业理化工程研究院 | The accurate measurement method of sweep trace of electron beam |
Also Published As
Publication number | Publication date |
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EP2314410B1 (en) | 2013-04-17 |
DE102009050521A1 (en) | 2011-04-28 |
US8314358B2 (en) | 2012-11-20 |
DE102009050521B4 (en) | 2023-02-16 |
CN102039483B (en) | 2016-05-11 |
CN102039483A (en) | 2011-05-04 |
EP2314410A1 (en) | 2011-04-27 |
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